xmas week 2025 - fresh strawberry sponge cake with mascarpone mousse

xmas week 2025 - fresh strawberry sponge cake with mascarpone mousse

• 19 Dec 2025

For Xmas Week 2025, I thought I'd include a showstopper. I bookmarked a few cake recipes in 'Beatrix Bakes:Another Slice' by Natalie Paull, but ultimately I decided upon this one, the fresh strawberry sponge cake with mascarpone mousse as it's strawberry season in Sydney. The cake can be made with other in season berries or fresh figs.

The original recipe made an 8 inch layer cake and the cake layers were baked in a large rectangular 40 cm × 30 cm × 2 cm tin, then cut to size. I didn't have a rectangular tin large enough so I baked the cake in a smaller tin. The cake took a little longer to bake then I removed the brown edges from the still warm cake with a small sharp knife. Once the cake was cold, I then split it horizontally.

The filling needs to set overnight so you'll need to make the cake and the filling the day before you plan to serve it, then unmould and decorate just before serving. 

Here's the recipe for you which makes a 17cm cake. If you'd like to make the 20cm cake, you can find the recipe here. For all my recipes, I use a 250 ml cup and a 20 ml tablespoon. All eggs are 60 grams and my oven is a conventional oven not fan forced, so you may need to reduce your oven temperature by 20°C.

Fresh strawberry sponge cake with mascarpone mousse – 17cm
Buttersponge cake
35g unsalted butter
Finely grated zest of ½ lemon
45g full cream milk
25g egg yolk (from approx 1 egg)
80g egg whites (from approx. 3 eggs)
½ tsp vanilla paste
50g self-raising flour 
pinch salt
1/8 tsp cream of tartar
55g caster sugar

Filling
1 quantity mascarpone mousse
120g strawberry jam (homemade or very good store-bought). Match the jam to the berries used
250g fresh, perfectly ripe strawberries/raspberries or blackberries, washed and hulled

Mascarpone mousse
150g good quality white chocolate finely chopped 
185g mascarpone
265g cream (35% fat)
6g titanium strength gelatine leaves + cold water
113g full cream milk
½ tsp vanilla paste
teeny pinch of fine sea salt

Strawberry sherbet dust – this makes more than you need
20g icing sugar
5g freeze-dried strawberries
¼ tsp citric acid

Cake
Preheat the oven to 170°C, conventional. Grease and flour a deep 17cm round tin and line the base with baking paper. 

Place the butter and lemon zest in a small saucepan over a medium–high heat and cook until the butter is sunshine yellow with white milk solids on the base. When cooked, pour the yellow butter into a wide mixing bowl, leaving the white solids behind, and immediately add the milk to cool the mixture down quickly. Hand whisk in the egg yolk and vanilla. 

Weigh the flour and salt into a small bowl and set aside with a sieve on top.
Put the egg white and cream of tartar in the bowl of an electric stand mixer. Using the whisk attachment, whip on speed 6 (medium–high) for 1–2 minutes, until the whites have changed from foamy to stiff and white. Start adding the sugar to the whites very gradually – about 1 heaped teaspoon every 20 seconds, so the whole process takes 3–4 minutes. It is imperative to the success of the cake that the meringue is so stiff you could carve a knife through it. After all the sugar is in, reduce to speed 1 (low) for 1 minute to even out the air bubbles. 

Sift the dry ingredients over the butter/milk/yolk mix and whisk in by hand to make a smooth paste, then gently and thoroughly fold in one-third of the meringue. Gently fold in the remaining meringue and do a final fold with a plastic spatula until no white streaks remain. Scrape the mixture into the tin and smooth the top, making a recess in the centre to control doming. 

Bake for 20-25 minutes until the top is pale gold. While the cake bakes, set up a cooling rack on your work surface and spray it with cooking oil. As soon as the cake is done, quickly run a knife along the unpapered sides and confidently flip the cake from the tin onto the cooling rack. Gently peel away the paper and set the rack over your sink (or carefully elevate) to get maximum cooling airflow beneath. 

While the cake cools, start the white chocolate and mascarpone mousse so it is still pourable when you reach assembly time. 

Mascarpone mousse filling
Beat the mascarpone and cream to soft slumpy peaks then refrigerate until needed. 

Soften the gelatine leaves in enough cold water to just cover them, and leave until the gelatine feels like soggy cling wrap. While it softens, heat the milk, vanilla and salt in a small saucepan until you get a bubbly boil across the entire surface. Squeeze out the gelatine leaves and add to the hot milk. Stir until dissolved. 

Place the chopped white chocolate into a medium bowl and pour over the milk mixture. Whisk to melt the chocolate. If it’s stubborn, heat in the microwave in 30 sec bursts until the chocolate has melted. Cool the mix at room temperature to around 23-25°C. Every 5 minutes or so, gently whisk and scrape down the side of the bowl with a flexible plastic spatula. Do this until the mix begins to set. This should take around 10–20 minutes – less time in colder weather and more when it’s 36⁰C! Gently fold the cooled chocolate mixture and chilled cream together.

Assembly 
While the cake cools, lightly spray the deep 17-cm round cake tin with oil spray, then line with baking paper. Invert the cooled cake onto a work surface and remove the baking paper, then carefully scrape off the browned cake edges with a sharp paring knife. Split the cake horizontally. Divide the strawberry jam between the two sponge cakes, spreading to the edges of the cake.

Place one round sponge cake into the lined cake tin, jam-side up. Pour in half of the mascarpone mousse mixture, then smooth out and tap lightly. Place the strawberries in concentric circles – “top to tail”. Pour over the remaining mascarpone mousse and gently shake to ensure it fills in the gaps of the strawberries. Flip the second sponge circle on top, jam-side down. Cover the cake with plastic wrap, then sit a flat plate (or tart tin base) on top with a weight on top (like a block of butter). Chill for at least 4 hours but overnight is best before unmoulding.

Strawberry sherbet dust
Place all the ingredients into a small food processor, blitz the ingredients to a powder.

To serve
Just before serving, peel the plastic wrap back to expose the cake. Place the serving platter on top, then invert onto the serving platter. Remove the tin and gently peel away the paper. 

Just before serving, sift a snowdrift of sherbet dust over the top of the cake, as the sherbet dust will liquefy a little when chilled and uncovered. Cut into wedges to serve.

Natalie can do no wrong as far as I'm concerned. She gently holds you hand as you make one of her recipes and if you follow her instructions, all will end well. This was a beautiful cake in every sense of the word

That was my final bake for Christmas week 2025. I was planning to post again on Monday but I'm not sure that I will.

For those of us who live in Sydney, the past week has been challenging and I'm still trying to come to terms with what took place in my own backyard.

Bye for now,

Jillian